I've seen this story twice, but finally I'm able to understand all story arcs, and boy, there are many.

For starters there's the intriguing story about a girl who plays detective in the palace in order to revenge the murder on her sister. She happens to sustain the weak and fight the bullies in the long run, and she gets help from a royal palace guard, the younger brother of the empress. This gentle, well behaved lady admires and loves the headstrong, self made girl, improving her status wherever she can, much to the annoyance of her own husband.

The emperor himself is frequently irritated by this unruly palace maid. Of course there's more than meets the eye and their developing relationship is the best story arc in my opinion, giving some comic relief as well.

Since this is a story about the palace there are the usual vicious schemes of the women in the harem, their characters are really fleshed out, and there's also the harem-in-reverse theme: our heroine is loved by several men. Not that typical is the sound and fulfilling ending of the series, which is great. Highly recommended!